Combination fuse cutout and switch



R. H. AMUNDSON COMBINATION FUSE CUTOUT AND SWITCH Dec. 22, 1953 5 Sheets-Sheet 1 Filed May l2, 1951 I N VEN TOR.

zzorhy jaaa Zd 167m un son Dec. 22, 1953 R. H. AMuNDsoN COMBINATION FUSE CUTOUT AND SWITCH 3 Sheets-Sheet 2 Filed May 12 1951 INVENTOR. Roald HHmL/,nolson lllfllll BY HZZorrz' DeC- 22, 1953 R. H. AMUNDsoN COMBINATION FUSE CUTOUT AND SWITCH 5 Sheets-Sheet .'5

Filed May 12, 1951 I 5 lars. 4:51a; r4... rally/gym.

, INVENTOR. RoaZoHmunoZson Patented Dec. 22, 1953 UNITED STATES PATENT OFFICE COMBINATION FUSE CUTOUT AND SWITCH Application May 12, 1951, Serial N0. 226,077

17 Claims. 1

My invention relates to a combination fuse cutout and a switch for controlling an electric circuit.

It is an object of this invention to provide for a bayonet type combination fuse cutout and circuit closer in an electrical distribution syst-ern, a fuse which in one part will react to a low steady overload and in the other part will react to a current of greater magnitude over a shorter period of time, and which bayonet can be rotated t-o close the circuit only after rupture of the fuse.

Also an object of my invention to provide in a primary transformer bushing a combined dual purpose ruse and circuit closer means whereby on rupture of the fuse under either of tr-.fo abnormal conditions in an electric circuit, the circuit may be closed by inanual operation of the circuit closer.

Another object of my invention is to provide in a primary transformer bushing a dual purpose fuse and circuit closer consisting 'of a flexible link which is fusible in its rst part when the temperature ol the oil or other substance in which it is immersed reaches a value indicating sustained overload and is fusible in the second part by a load or dangerous over-current but which is insuiiicient in duration to raise the teinperature of the dielectric medium in which it is immersed to a value that would fuse the first part, and includinc'means exteriorly oi the bushing for manually operating the circuit close' to close the circuit aiter the uselhas ruptured.

A. further object of this invention is to provide in a primary transfo-inner bushing a bayonet type combination fuse and recloser, the fuse having' dual characteristics operable under either or tivo abnormal circuit conditions and the recloser be ing manually operable to reclose the circuit upon rupture oi the iuse under either of the abnormal conditions.

Still another object is to provide a bayonet type fuse and circuit closer which has two circuit closing positions, one of 'which disposes the in circuit closing position, and the other of which disposes the circuit closer in circuit closing position, said latter position being manually selectonly after rupture oi the fuse.

Further, it is an object 'to provide in a trans former a a fluid insulating material therein, a tubular transformer bushing extending' from the exterior "or" the casing and into the iiuid therein and -a bayonet insert-able in the bushing and comprising a fuse Velement fusible by excess currents and by duid tem-peratures 'exceeding a given value, the bayonet 'in- Vcluding a circuit reeloser operable to reclose the circuit after interruption by the fuse element.

Other objects will appear from time to time in the course of the specification and claims.

The dual characteristic fuse and circuit closer disclosed herein is in its broader concept the invention of William D. Kyle, J r., whose application Serial No. 222,849, filed April 25, 195i, is copending herewith and is assigned to the same assignee of the present application.

Referring to the drawings:

Fig. 1 is a Vsectional view tairen longitudinally on the axis of an embodiment ci this invention.

Fig. 2 is a diagrammatic view of an electrical transformer and a combined fuse and circuit closer embodied therein.

Fig. 3 is an enlarged fragmentary view in section of the lower part of Fig. l showing the fuse blown and the bayonet rod moved axially into position to close the circuit.

Fig. 4 is a fragmentary view in section taken longitudinally on the axis of another embodiment of this invention.

Fig. 5 is a view partly in section taken longitudinally on the axis of a third embodiment of this invention.

Fig. 6 is a fragmentary View in elevation showing the bayonet operating handle in circuit closing position through the fuse.

Fig. 7 is 'a fragmentary View in elevation showing the bayonet operating handle in circuit closing position after rupture of the fuse.

Fig. 8 is a fragmentary sectional view taken relatively on the line 8-8 of Fig. 5 but showing the fuse ruptured, the detent out of locking position, and the switch rotated to circuit closing position.

Fig. 9 is a bottom view of the lower end of the bayonet relative to Fig. 8 as it appears before the fuse has blown.

Fig. l0 is a fragmentary sectional view of the -lower part Aof the bayonet shown in Fig. 4 as it appears when the fuse is ruptured and the switch is rotated to circuit closing position.

Fig. 11 is an enlarged fragmentary sectional View of that portion of the embodiment shown in Fig. 4 which is intermediate the end of the fuse section.

Like parts are indicated by Vlike reference nu merals in all the various views.

as indicated in Fig. f2 the distribution transiorrner consists of a primary winding l, a secondary winding V2, and a transformer core 3. The secondary winding 2 is grounded at 'l and is connected to service lines 5 which terminate at secondary bushings il. [l combined fuse and switch embodying invention is shown dianinatically at S with a protector fuse S in series located between it and the winding i. Outside the easing is a lightning arrester or expulsion gap 5S, located hetween each primary lead i i and the casing A tank discharge gap is shown at i2.

Fig. l shows in detail one embodiment of the combined fuse and switch shown diagrammatically at S in Fig. 2. The insulating bushing i3 is preferably made of porcelain and is provided with skirts it on the upper section and a tubular insulating sleeve or extension at its lower end. A rnetal sleeve 33 rits over adjacent annular shoulders on the bushing i3 and the sleeve Sii and is spun over the shoulders at its ends to hold the bushing and extension together.

The transformer bushing lil is mounted in an opening in the annular boss it on the transformer casing l and sealed in position by means not shown, with the sealing means 3i? making the` connection air tight. At the upper end o the porcelain bushing is a terminal or ierrule shaped on one side so as to provide means for attaching the primary lead at 23. A cement 3i is injected between the ferrule 5t and the hushing i3 to securely fasten thein together. The ierrule 5t has a reduced tubular end providing an opening 5i substantially c-o-axial with the bore in the bushing i3. The handle 52 extends through the opening 5i is normally held against movement downwardly relative to Fig. l by a latch 53 which is pivoted at 52a on the handle and normally engaged at its lower end with a collar By pulling on an 5t of the latch 53, t e latch will move into the channel 55 in the handle The collar is threaded on the cap E@ and as indicated forms a rest for the lower end of the latch 5i?. A gasket S5 forms an air tight seal between the collar the ferrule 5d, and the handle 52. On the under side of the ferrul-e t@ and adjacent its opening 5l, a plurality of contact fingers lil are secured thereto and extend downwardly and inwardly so as to contact the rnetal handle 52. As may be seen the lower end of the handle is provided with an annular shoulder l@ which cooperates with the iingers l@ to releasably latch the handle against upper movement. A conductor rod il is attached to the lower end of the handle at 5d by some pinning means it or other suitable means. At the lower end of conductor rot. 255 is the dual characteristic fuse and switch.

This dual characteristic fuse and switch coni- -prises a sleeve oi some conducting material such as crass in its upper portion secured to bushing nut which is threaded on the threaded end 2e oi the rod As may he seen in Figs. l and 3, the sleeve 5?; has a libre sleeve E@ secured to and extending from the lower end. The inner diameter of the sleeves is the same but the outer diameter of sleeve te is slightly greater than that of sleeve te.

At the lower end of the libre sleeve l is secured a contact rerrule @i having a terminal lug t2. Resilient contact fingers iid attached by means of an encircling terminal ring l@ to the insulating pushing engage the ierrule Si. The transformer terminal wire t@ is secured to the ring Extending from and secured to the bushing nut et is a ilexible conductor cable @E which is secured at its lower end to a resistor @il having a terminal tongue 63 secured by a solder @l or other rnetal of low melting temperature characteristics, to the terminal lug S2. .A coil spring Se is secured at one end to the bushing nut 3Q and at the other end to the resistor 5@ and is maintained in tension and thereby stresses the connection between the tongue E3 and the lug @2. Although l have suggested that the solder til be characterized by a low melting temperature, it will he understood that higher temperatures may ce desirable and, therefore, the choice oi materials for connecting the tongue and the lug lill rest with the designer and the results desired.

li the temperature of the oil or other medium in the transformer casing reaches a given teinperature suihcient to melt the solder as it will with an overload of long duration, the spring Si.; will separate the tongue @3 and the lug E2, and collapse the cable and draw the resistor ed upwards in the sleeve @il thus producing a gap and interrupting the circuit. li the temperature of the resistor ifi is raised suiciently hy a sudden surge of current sufficient to damage transformer insulation if continued 'out which might not he or sufeient duration to warm the transformer oil, t Le heat will be transmitted through the tongue to the solder 5l'. When the solder is softened sufiiciently to allow the spring il@ to separate the tongue and the lug v'ifl and collapse the ilexilole cable the resistor 5d will oe drawn upward in the sleeve thereoy producing a gap and interrupting the circuit.

When the circuit has been interrupted under either of the conditions noted, it 'may be reclosed hy pulling the hook-like latch releasing arm or handle 5d down so that the lato will he rnoved from the collar 55 and into the space 55. The conductor handle 52 is then freely movable downward into the bushing i3 until the conductor sleeve 59 makes contact with the resilient oontact lingers 68 as shown in Fig. 3. This rees-tairlishes the circuit through the handle rod sleeve 5S, resilient lingers @d and the lead oii line tu.

In Fig. 4 I show a second embodiment of my invention. At the top or the bushing i3 l show a substantially dat topped cover or closure lli having a centrally located conductor hub 2@ projecting into the bushing. A terminal ierrule il having a terminal clamp 23 is secured to the bushing by means or" a ceinentitious material 3l and has a central opening it .co-axial with the bore of the bushing and receiving the hub A gasket 2l seals the opening li and the closure lli is provided with an operating eye 22 integral therewith.

The lower end oi the bushing ill is provie with an insulating sleeve 32. A.. metal sleeve l fits over adjacent annular shoulders on the hushing i3 and the sleeve 32 and is spun over the shoulders at its ends to hold the bushing i3 and sleeve 32 together. The manner of mounting the bushing in the container i is similar to that illustrated in Fig. l.

On the under side of the rerrule il' adjacent its opening ES a plurality of contact fingers is are secured thereto and extend downwardly and inwardly so as to contact the conductor hub 2t. As may be seen the lower end of this conductor hub 2S is provided with annular shoulder 20a which cooperates with the lingers i@ to prevent upward movement oi the bayonet.

To the conductor hub 2li is attached a conductor rod 2d by some pinning means Se. at the lower end of the conductor rod 2d is a threade ed portion 25 which is connected with the dual characteristicifusefand.switchihereafterdescribed- This .combination fuse-.and zswitch .is surrounded by fa kiibre .sleeve 12.6 having Va :radially disposed Venting slot 26a. A .conductor strap 2-1 'prefierably made .of copper Yextends vacross the top and :down :one side .of the .fibre .sleeve i215 and is secured to the .upper end :of .theesleeveby means of '.the :bushing nut .2;9. `This conductor ystrap 21 .is .ou-t of .contact `as a iconductor -when in 'the position shownv in ,'Fig. 4.

The bushingnut :29 .encased ywithin the :upper section of the 'fibre fsleeve 2 6 towhich itrisfastened .byakey means 1| 'is in .direct :contact with the conductor rod 24 and rstrap 2.1. :Inserted into the bore .4| of the bushing nut29 :and secured therein :by means .of .-a V.lowmelting:solder is a flexible ,link .40 of the .dual .characteristic ffuse, the low .melting solder joint being .responsive to the temperature of the cooling medium inthe transformer casing. A .coil spring v-42 surrounds the ilexible link 4D and maintains tension thereby inthe link -as long as the link remainsjoine-d at lIH. The lower ends of the link lll) and the spring r.42 -are anchored to a spacer :48. This spacer 48 is of suiiicient diameter to :loosely -ll the bore -within the bre sleeve 26 andis provided with a vertical extension 48a to 'which thelink 4.0 and spring 42 are secured.

The second flexible link .4-3 of the dual .characteristic fuse and the surrounding .coil spring 44 are secured at their upper ends to the eX- tension 48h on the spacer 48. The lower ends ofthe link V43 and spring 44 are .attached to -a rod 44a which extends into vthe bore 45 in the resistor V,terminal a. secures the rod-44a to the resistor terminal 45a which `is a unit part of Yresistor :element 4,1. The lower end .of .the ,resistor .41 is provided with a terminal contact or plug 12 :secured-in the lower end of the sleeve 28 bymeans of pin 1 I. When the fuse .and switch assembly .is .in Vassembled relationship asshown Yin `Fig. 4, V.the springs 42 and .44 are yunder tension and -jointl-yzstress the soldered joints .4| and A6. When current in eX cess of .a Ypredetermined value passes through the resistor .41 heat ,generated in the lresistor will be .conducted to lthe solder joint vM5 and soften it suihciently to permit the springs 42 and 44 .to withdraw the rod .Maand introduce a lgapin the circuit of suiiicient .length to cause the .current U to lbe broken.

Below .the .metal plug 1.2 .and .contacting it .is a contactrplate 1,3 which serves as a guide and has a terminal rod 14 which extends to the eX terior of the lower-end .of .the sleeve :32. the plate .13 and the vlower enclosure of the .insulating extension 32 is a .coil spring 15 surrounding the terminal .rod '14 .and lurging the plate 13 in iirm .contact with the plug 12. A lead '16 is connected with the terminal rod 14 and with the auxiliary viiexible Aconnection '11 electrically joined with the contact member .2 8. .After the .'fusehas blown at either V.4l .or 4.6, the circuit can be closed by rotating the handle 22 which switches the position vof the conductor strap 2.1 from that shown .in Fig. 4 `to that show-n in Fig. 1G so as to reclose -the `circuit vthrough the contact piece l2.8.

Adjacent thespacer 4.8 `opening 49 in the Alibre fuse tube 26, of suflicient vdiameter to :hold f a detent 18 with .its surrounding spring 19. Fig. 11 is an enlarged view v.of this. The head of the detent 18 is held tightly against the spacer 4B .by the spring 19, and the other end ofthe Idetent extends into the vslot 80 .of the insulating sleeve Solder 46 in the bore 45 Between 32. 'When 'the-detentextends linto the 'slot 8G, the 'bayonet .is locked against rotation in the bushing |.3. yThe detent will remain in this 'position .untileither of thejoints 4l or 4S lcollapses and interrupts the circuit. The detent is then moved out Tof the slot and into the bore of theiibre :sleeve 26. This frees the bayonet for rotation inthebushing by means of the handle and cover.

Fig. 10 illustrates what happens when the solder V.connecting .the lower link 3 of Fig. li to the nietalcontact piece 45aY melts et 46. The springs 4'4 and -42 recoil upwardly, the flexible cables '4D Vand 4-3 and the vspacer 48 move upwardly with the .springs and the spring held detent 18 moves zout of its locking position inwardlyxin the bore `of the bre sleeve 25. The movement inward of the detent 18 allows the handle 22 vwith its integral closure member I4 and associated elements to be rotated in the bushing 'so that the conductor ystrap 2'. will engage the contact member 23 and thus direct the current from conductor `rod 24, through the conductor strap 21 to the Contact piece and conductor 'l'lto the lower terminal 16.

A'thirdzembodiment of this invention is shown inFigs. 5 and 8, the two views are taken at 90 from each other, in 'ig. 8 the fuse has ruptured and the conductor strap rotated to close the circuit. This embodiment is substantially the same as Fig. 4 in the upper part of its construction yand `in the vrotation of the circuit maker and breaker. In the Fig. 5 structure an insulating sleeve having diametrically disposed slots 38a is secured to the bushing i3 by means oi a sleeve 3,3. A vbushingnut 33 extends into the upper part of ibie sleeve 82 and is in threaded engagement with conductor rod 24. The lower end of fibre sleeve 82 is provided with a contact ferrule 5l having a terminal lug '62.

Resilient Contact fingers 53 attached by means of 4an encircling vtermina-1 ring S3 to the insulatingsleeve 38 extend into the slots 38a and engage .the ferrule 6l. As indicated in Fig. 8 the transformer terminal wire e3 is secured to the ring S3. xtending v'from and secured to the bushing nut 3 9 Vis a exible cable 65 which is secured at its lower .end to a resistor 54 having a terminal tongue '63 secured by a solder Si or other metal -of jlow melting temperature characteristics, to the terminal lug G2. A coil spring 55 is secured at one end A'to the bushing nut 3S and at the other end to the resistor '54 and .is maintained in tension and'thereby stresses the connection between the ton-gue y63 and the lug 52.

If the temperature of the oil or other medium in the transformer casing reaches a given teme perature sufficient to melt the solder 51 as it will with an `overload of long duration, the spring 56 will separate the tongue E3 and the lug 52, and collapse the cable S5 and draw the resistor 54 into the .sleeve :82 thus producinga and intcrrupting the circuit. If .the temperaturen?? the resistor 54 is :raised :sufficiently Aby a current of a vrmagnitude suflicient to damage transformer' .insulation'if :continued but which might not be of suiiicient duration to warm the transformer oil, the heat will ,be transmitted through the tongue 63 to the solder 61. When the solder is softened sufliciently to allow the spring 55 to separate the tonguel .and thelug A62 Vand collapse the dexible cable '6.5, theresistor E4 will be drawn into the sleeve .50, thereby producing a gap and interrupt- .ing the circuit.

Referring to Fig. 8, when the spring '65 recoils in the libre sleeve 52 rcarrying with it the flexible coil 65 and the resistor Erfi, the detent 3| held by spring means moves into the core of the sleeve 82 out of the locking slot 38h in the insulating sleeve 38. The movement of the detent out of locking position allows the bayonet to be rotated so that the conductor strap 2l maires contact with contact piece Bti to close the circuit subsequent to rupture of the fuse.

Since the resilient contact fingers t8 are at right angles to the conductor strap 2l, contact point vBri and the lead orf line es they do not appear together in the same section view. The resilient contact fingers 55 appear in Fig. -5 and the conductor strap 2 and contact point Se along with the lower terminal or lead olf line 9 ap-` pear in Fig. 8. Fig. 9 shows their relative position from the bottom.

When the fuse section in either of the modied forms of my combination fuse cutout and switch has been ruptured, the bayonet type closer may be withdrawn from the bushing and the fuse section replaced by disconnecting it from the threaded end 25 on the rod ift and connecting a new unit thereto. During the interval that the fuse is being replaced, the transformer will be de-energized but such operation may be carried on without disturbing the conductor connections on the bushing.

The use and operation of my invention are as follows:

The three embodiments of my invention are based on the same principle of using a bayonet type fuse and switch in a primary transformer bushing and utilizing a dual characteristic fuse link which will respond to two kinds of abnormal circuit conditions and which. when the fuse blows from either of these abnormal circuit conditions the bayonet type fuse rod can be adjusted manually to close the circuit. If there is a long overload on the line it will warm the transformer oil to a sufficient degree to melt the solder which holds the exible coil in closed circuit. Or if there should be a current of great magnitude on the line that may be of insufficient duration to warm the transformer oil but be suiiiciently great to damage the transformer insulation, this current will create heat in the resistor which heat will be transmitted to the solder joint and melt it. When this solder connection melts the electrical circuit is broken. The forms shown in Figs. i and have one solder joint that responds to two kinds of abnormalities, and the form shown in Fig. e has two solder connections, one respondingto one kind of abnormality and the other responding to another kind of abnormality.

In all three types the circuit can be closed manually by either rotating the handle or by releasing a latch and dropping the handle. In this manner it can be seen that the electric service along the lines can be readily renewed.

To replace a blown fuse it is necessary to lift the bayonet type closer from the transformer primary bushing using a hot-line stick. The old ruptured link is then removed from threaded end 25 of rod 2li and a new linl.` screwed thereon. The bayonet is then reinserted into the transformer bushing effecting reclosing of the transformer primary input circuit.

claim:

l. In an electrical apparatus including a casing and a dielectric iiuid therein, the combination with a tubular terminal bushing projecting from the exterior to the interior of said casing, said bushing including a line terminal on the exposed end of said bushing and a transformer lead terminal on the concealed end of said bushing, of a bayonet type circuit closer projecting into said bushing and having a contact at one end engaging with said line terminal and a contact at the other end engaging with said transformer lead terminal, said closer including a conductive assembly electrically connecting said contacts and comprising a dual characteristic fuse section immersed in said uid and a resistor in series with and heat transfer relation to said section, said section characterized by its selective response to ambient temperatures of said fluid in excess of a predetermined value or to temperatures of said resistor in excess of a predetermined value.

2. In an electrical apparatus including a casing and a dielectric fluid therein, the combination with a tubular bushing extending from the exterior to the interior of said casing and having a terminal at each end of said bushing, of a bayonet type closer projecting into said bushing and including a fuse normally electrically connecting said terminals and a switch normally in open circuit position, said fuse comprising a fusible section immersed in said iiuid and a resistor in series with and heat exchange relation to said section, said closer being manually movable in said bushing afterrupture of the fusible section to electrically connect said terminals through said switch.

3. In an electrical apparatus including a casing and a dielectric fluid therein, the combination with a tubular bushing extending from the exterior to the interior of said casing and having a terminal at each end of said bushing, of a bayonet type circuit closer projecting into said bushing and including a fuse electrically connecting said terminals, said fuse comprising two relatively spaced fusible sections in series relation and immersed in said fluid, spring means interposed between said sections and maintain ing a stress thereon tending to rupture sections, and. a resistor in series with said sections and including a heat conducting portion engaging one of said sections, the other or said sections being responsive to ambient temperatures of said fluid in excess of a predetermined value.

4. In an electrical apparatus including a casing and a dielectric uid therein7 the combination with a tubular bushing extending from the exterior to the interior of said casing and having a terminal at each end of said bushing, of a bayonet type circuit closer projecting into said bushing and including a fuse electrically connecting said terminals, said fuse comprising two relatively spaced fusible sections in series relation and immersed in said fluid, spring means interposed between said sections and maintaining a stress thereon tending to rupture said sections, and a resistor in series with said sections and including a heat conducting portion engaging one of said sections, the other of said sections being responsive to ambient temperatures of said fluid in excess of a predetermined value, said closer also including a switch normally in open circuit position and movable through the agency of said closer to closed circuit 4position electrically connecting said terminals after rupture of said fuse.

5. In an electrical apparatus including a cas ing and a dielectric uid therein, the combination with a tubular bushing extending from the exterior to the interior of said casing, oi a bayonet type circuit closer projecting into said bushing: and comprising a fuse and a. switch, said closer having a first and a second' position in said bushing, and releasable latching means nor'- m'ally' interposed between said closer! andY bushing and retaining said closer in saidrstV position closing a circuit through said fuse, said closer being movable to said second position closing said circuit through said switch upon release ofA said latching means.

6. In a electrical apparatus includingA a casing and a dielectric iluid therein, the combination with atubular bushing extending from the efr-- terior to the interior of said casing, of a bayonet type circuit closer projecting into said bushing and comprising a fuse and a switch, said closer' having a rst and a second position in' said bushing, and a latch normally interposed between said closer and bushing and latching said closer to said bushing in said iirst position closing a c'rcuit through said fuse, said latch biased to release said closer and normally held in latching position by said fuse, said latch being released only'upon rupture of the fuse and said closer thereafter mov-Y able to said second position closing said circuit through said switch.

7. The combination with an elongated tubular housing having a terminal at each end, said housing having a longitudinal slot interiorly at one end, cfa bayonet type circuit closer inserta'blein' said housing for electrically connecting said terminals, said closer including a fuse normally electrically connecting said terminals and com-- prising an insulating tube, spaced fusible sections in said tube, a ilexible cable connecting said fusible sections and having an intermediate enlarged portion, a detent carried by and projecting through the wall of said tube and into said slot in radial relationship to said enlarged portion of said cable, said detent biased out of said slot and said enlarged portion normally holding said detent in said slot, a pair of coil springs encompassing said cable and each disposed' on a side of said enlarged portion opposite that of the' other, one of said springs under tension between said enlarged portion and one of saidV fusible sect-ions, the other of said springs under tension between said enlarged portion the other of said' fusible sections, said enlarged portion movable alternativelytoeither side ofv said detent upon rupture of eitherV fuse section,v and a switch` carried by said closer in normal open circuit.

relationlto'said terminals'and closable onlyupon rupture oi said fuse, said closer rotatable in said housing to electrically connect said terminals through said switch subsequent to release of said detent, one of said fusible sections .responsiver toY predetermined ambient temperatures and the other or Vsaid Vfusible* sectionsV responsive to predetermined transient electric currents.

8. The combination with an elongated tubular housing having a terminal at each end, said housing having a longitudinal slot interiorly at one end, of a bayonet type circuit closer insertable in said housing for electrically connecting said terminals, said closer including a fuse normally electrically connecting said terminals and comprising an insulating tube, spaced fusible sections in said tube, a flexible cable connecting said fusible sections and having an intermediate enlarged portion, a detent carried by and projecting through the wall or said tube and into said slot in radial relationship to said enlarged portion of said cable, said detent biased out of saidslot and said enlarged portion normally holding said detent in said slot, a pair of coil springs encompassing said. cable and each disposed on a side of' said enlarged portion opposite that of the other, one of said springs under tension between said enlarged portion and one of said fusible sections, the. other of said springs under tension between said enlarged portion the other o said fusible sections, said enlarged portion movable alternatively to either side of said det-ent upon rupture of either'iuse section, a resistor in series withsaid fusible sections and having heat transier means engaging said one of said sections, and a switch carriedr by said closer in normal open circuit relation to said terminals and closable only upon rupture or said fuse, said closer rotatabie in said housing to electrically connect said terminals through said switch subsequent to release of said detent, said one of said fusible sections responsive to predetermined temperatur-es ci said resistor incident to transient electric currents andthe said other of said fusible sections responsive to predetermined ambient temperatures incident to continuing overload electric currents.

9. ln a protective device for an electrical appa ratus including a casing and a cooling medium therein, the combination with a tubular bushingA having a line terminal at one end and an apparatus terminal at theother end, of a circuit closer movably mounted in said bushing and including` a dual characteristic fuse and resistor in series relation to each other electrically connecting said terminals, ruse embodying a section fusible in response to prede ermined ambient temperatures of said cooling medium and a second section fusible in response to a predetermined rise in the temperature'of said resistor in excess of said preletermined ambient temperatures, and a conductor carried by said circuit closer in open circuit relation' to said tei oinals when said fuse and resistor are in closed circuit relation to said terminals, said closer being movable in said bushing to'place said conductor in closed circuitrelation tro-said terminals after rupture oi said fuse.

lO. Ina protective device for an electrical apparatus including a casing, the combination with atubular bushing having a line terminal at one end and an apparatus terminal at the other end, ofa circuit closer insertable in saic bushing adjacent said line terminal and including a dual characteristic fuse and resistor in series relation normally electrically connecting said terminals, and a conductor carried by said closer in open circuit relation to said te minals when said fuse is normally in circuit closing relation to said terminals, said closer rotatable in said bushing upon rupture oi said fuse to reclose the circuit through said conductor, said dual characteristic ruse being selectively responsive to ambient temperatures in said casing incident to the duration of a predetermined continuous overload currents insaid apparatus or to temperatures in said resisu torincident to predetermined current values of shorter duration than and inexcess of said overn load currents.

l1. Aitubular bushing for a ratus casing, said: bushing inc minal' at one end andan the-other enclin combination with telescopios-illy movable and rotatab e ing adjacent the li e terminal, inga dual characteristic fuse carri electrically engaged at one end with minal and; at the other terminal, said iuse being s ectively responsive to predetermined ambient temperatures and to prei eleotricalappaaline 'ter-v endiwith apparatus determined abnormal surge currents, and a switch member carried by said closer in electrical connection with said line terminal and normally out of electrical connection with said apparatus terminal, said bushing having a portion provided with a slot extending longitudinally interiorly thereof, a detent carried by said closer and normally held by the fuse in said slot and locking the closer against rotation until said fuse link ruptures, said detent biased to move out oi locking position and release the closer for manual rotation, whereby the switch member carried by said closer is moved into electrical contact with said apparatus terminal.

l2. A tubular bushing for an electrical apparatus casing said bushing including a line terminal at one end and an apparatus terminal at the other end, in combination with a circuit closer movable in the bushing relative to said terminals, said closer including a dual characteristic fuse electrically engaged at one end with said line terminal and at the other end with said apparatus terminal, said fuse carried by said closer and characterized by its selective response to predetermined ambient temperatures and to predetermined abnormal surge current, and a switch member carried by said closer in electrical ccnnection with said line terminal and normally out of electrical connection with said apparatus terminal, a detent normally held by the ruse in a locking position interposed between saidv closer and bushing and biased to move out of locking position upon subsequent rupture or" the fuse to release said closer for movement to electrically engage said member and apparatus terminal.

13. A terminal bushing for a transformer casing said bushing including a line terminal at one end and a transformer terminal at the other end, in combination with an electrical closer insertable in said bushing adjacent said line terminal and including a dual characteristic fuse carried thereby and normally closing the circuit between said terminals, said fuse comprising two relatively spaced fusible sections one of which is characterized by its response to predetermined ambient temperatures resultant to continuing overload currents in the transformer and the other of which is responsive to predetermined transient currents in the transformer, a flexible conductor cable electrically connecting said fusible sections in series, a coil spring surrounding said cable and subjecting said iuse sections to tension, and a switch member carried by said closer in electrical connection with one of said terminals and normally in open circuit relation to the other of said terminals, said closer movable in said bushing to electrically connect said member and said other of said terminals subsequent to rupture of one of said fusible sections.

1d. A tubular insulating housing having a first terminal at one end and a second terminal at the other end, in combination with a circuit closer inserted in said housing adjacent said rst terminal and including a fuse carried thereby and normally electrically connecting said terminals, said fuse characterized by its selective response to predetermined ambient temperatures incident to continued overload currents of a value insufficient to rupture said fuse or to predetermined transient electric currents of predetermined values in excess of said overload current values, spring means carried by said closer holding said fuse tensioned, a switch member carried by said closer normally in electrical connection with one of said terminals only, and detent means normally interposed between said housing and closer to hold said fuse in circuit closing position and said switch member in open circuit position, said detent means held in its interposed position by said fuse and bias therefrom for movement upon rupture of the fuse, said closer being movable in said housing to electrically connect said terminals through said switch member subsequent to rupture of said fuse.

15. A circuit interrupter comprising a dual characteristic fuse having a rst .fusible section and a second fusible section in series therewith, and a resistor in series with said sections and including a heat transmitting portion connected to said second fusible sections, said rst fuse section characterized by its response to ambient temperatures of predetermined values and said second fuse section responsive to predetermined temperatures of said resistor.

16. A circuit interrupter comprising an insulating support having relatively spaced terminals, in combination with a circuit closer morably spanning said terminals, said closer einbodying a fusible section and a resistor in series with each other and normally e eotricaliy connecting said terminals, fusible section characterized by its selective response to ambient temperatures in excess of pre-determined values or to resistor temperatures in excess ci predetermined values, and a switch member carried by said closer and normally7 in open circuit relation to said terminals, said closer upon rupture of said fusible section being movable to reclose an electric circuit by electrically connecting said terminals through said switch member.

1'?. In a circuit interrupter and recloser, the combination with a bushing having a pair of spaced terminals and interiorly a slot projecting longitudinally thereof, of a bayonet type circuit closer projecting into the bushing and including a fusible section, a resistor connected in series with said section by means or" a conductive means, and a switch, said closer having a first and a second position and rotatable therebetween in said bushing, said fusible section and resistor electrically connecting said terminals when said closer is in said rst position and said switch electrically connecting said terminals when said closer is in said second postion, iusicle section selectively responsive to temperatures in excess of a predetermined value incident to ambient temperatures or resistor temperatures, a detent carried by said closer and normally latching said closer in said first position and held by said iusible'section in said slot, said detent to move out of said slot upon rupture of said fuse section, whereby upon rupture oi said fusible Section said closer is rotatable to said second position to electrically connect said terminals through said switch.

ROALD H. AMUNDSON.

Brown et al. Aug. 24, 

